Extension Educator, Horticulture
Expectations. We all have them. But just like the man who called the escort service expecting a date for the opera but instead got a hairy armed guy driving a truck topped with a flashing yellow light, our expectations don't always translate into reality.
Hibiscus are popular garden flowers, but it's confusing to know what to expect from them. Will they live outside through the winter? Will they live in a container in the house? It all depends. Most of the over 200 different species of herbaceous and woody hibiscus are tropical or subtropical. Many hibiscus are not winter hardy, but some are native to Illinois so our winters come naturally.
Generally hibiscus are known for their large showy flowers often of very bright colors. The male and female flower parts are held as a dominant column in the center of the funnel-shaped flower. For the most part hibiscus are all sun and moisture lovers. Beyond that, it's hard to know what to expect from hibiscus.
One that is blooming right now in many landscapes is the shrub hibiscus, better known as Rose-of-Sharon, Hibiscus syriacus. Winter hardy to zone 5 it can, however, experience stem dieback after a rollercoaster winter. The 3-4 inch flowers of white, red or purple, usually with dark "eyes", are borne abundantly along stems for several weeks in summer. Leaves are three-lobed and dull in contrast to the glossy leaves of tropical hibiscus. Hibiscus shrubs can reach twelve feet tall, but a good prune in spring can keep them smaller. A 30-mph identification feature is their extreme vase shape and their multitude of summer flowers. Shrub hibiscus looks best in the back of a flower border with an apron of perennial flowers.
Hardy Hibiscus, Hibiscus moscheutos, is native to Illinois and most of eastern U.S. Rotund and robust, hardy hibiscus is known for its large leaves and large flowers. Plants are generally 2-3 feet tall but can reach 6 feet tall and do not form woody stems. Leaves can be 4-10 inches long and flowers can be 10 inches wide in some hybrids. Flowers may be white, pink, and shades of red, often with darker center "eye". Unfortunately Japanese beetles also love the flowers.
As with other herbaceous perennial plants the stems die to the ground each year. Hardy hibiscus is late to emerge in spring so don't give up on them too soon. Many hybrids exist but some good performers include 'Candy Stick', 'Clown', 'Pink Giant', and 'Sleeping Beauty'. For an excellent discussion of hibiscus cultivars check out Chicago Botanic Garden http://www.chicagobotanic.org/plantinfo/index.php
The glossy lobed leaves and brightly colored flowers of tropical hibiscus, Hibiscus rosa-sinensis, make these popular plants in southern landscapes and northern housescapes. The plant can live through cool but not cold temperatures; however, it needs heat to flower. If temperatures drop below 60 degrees, flowers are no longer produced until heat returns. Even cool nights will lessen flower production. Tropical hibiscus live happily indoors in a sunny warm spot.
To confuse us further another popular hibiscus found in garden centers has show-stopping leaves and barely noticeable flowers. The glossy red leaves of 'Red Shield', Hibiscus acetosella, are lobed to resemble a red-leafed silver maple. This is no shrinking violet since it can reach 8 feet tall. But if you want 'Red Shield' to come back next year, it will need rescue from winter's cold. Dig it before frost, plant in good potting soil, and grow it indoors as a houseplant in a sunny place.
Remember the gardener's mantra - save the plant label. It will help shape your expectations into reality.
Visit the Master Gardener Idea Garden on south Lincoln (just south of the corner of Florida and Lincoln Avenues) in Urbana to enjoy the beauty of several kinds of handsome hibiscus.